1. Field of the Invention
The present invention relates to a front structure of a vehicle, more specifically to a front structure of a vehicle comprising a toe board cross member which forms a closed cross section by cooperation with a toe board.
2. Discussion of the Related Art
A front structure of a vehicle comprises a toe board provided at a front part of the vehicle by extending in a widthwise direction of the vehicle for partitioning an engine compartment and a passenger compartment, and left and right front side frames, each extending in a lengthwise direction of the vehicle. The side frames are provided at a front part of the vehicle, and a part of the side frames are first brought into contact with the toe board, and then bent in a lower direction. The side frames extend to a lower surface of a floor of the vehicle. Heretofore, front suspension members are supported by the front side frames having such structure. Such technology is disclosed, for instance, in Japanese Patent Kokai Publication 6 (1994)-329045, FIG. 1.
FIG. 7 is a vertical cross section for explaining a prior art structure. The figure shows a front side frame 100 at a part corresponding to a front suspension member support portion 102. The cross section of the front side frame 100 viewed from the front or rear part of the vehicle body has approximately a U-shape. The front side frame 100 is connected to a toe board 110 via a flange provided on an upper part of the front side frame 100. Accordingly, the front side frame 100 and the toe board 110 form a closed cross section extending in a longitudinal direction of the vehicle. The supporting portion 102 is provided on a bottom wall 101 of the front side frame 100. Thus, a rear part of a front suspension member 103 is supported by the front side frame 100 via the front suspension member support portion 102.
Moreover, it is possible to provide a toe board cross member in front of a toe board. In this case, a structure with a closed cross section extending in a widthwise direction of a vehicle is formed by cooperation of the toe board cross member with the toe board. Left and right front side frames are connected by the structure with a closed cross section, whereby the rigidity of the front structure of the vehicle is increased, as is disclosed, for instance, in Japanese Utility Model Kokai Publication 61 (1986)-159286, FIGS. 1 and 2.
When a vehicle turns a corner, force in a widthwise direction of the vehicle is applied to the front suspension sub-frames 103. Then, the force is successively transmitted to the support portion 102 and the front side frames 100. Accordingly, such force F applied in the direction of the vehicle width may cause a slight deformation of the closed cross section in the widthwise direction as shown by a chain double-dashed line. The slight deformation can cause the geometry of the front suspension members to change. Namely, the driving stability of the vehicle can be affected by the deformation.
The conventional structures with the closed cross sections absorb flexion or distortion relatively caused between the left and right front side frames. However, it is impossible to prevent the structure with the closed cross section itself from being subjected to the slight deformation caused by a force applied in the widthwise direction of the vehicle.
It is therefore an object of the present invention to provide a front structure of a vehicle which improves the rigidity of the vehicle in the vicinity of front suspension member support portions, and hence prevents front suspension members from changing geometry and increases driving stability of the vehicle. The invention includes a toe board extending in a widthwise direction of the vehicle, the toe board being provided in a front part of the vehicle for partitioning an engine compartment containing a power unit therein and a passenger compartment, a pair of front side frames provided by being spaced apart from each other in a widthwise direction of the vehicle, the front side frames extending in a lengthwise direction from a front part of the vehicle to a lower surface of a floor of the passenger compartment, the front side frames being downwardly bent when contacting the toe board, a toe board cross member extending in a widthwise direction of the vehicle between the front side frames so as to connect the front side frames with each other, the toe board cross member and the toe board defining a structure having a closed cross section, and front suspension member supports provided on the front side frames, the toe board cross member extending to positions in the vicinity of the front suspension member supports.
Another object of the present invention is to provide a front structure of a vehicle which further improves the rigidity of the vehicle in the vicinity of front suspension member support portions, and hence prevents front suspension members from changing geometry and further increases the driving stability of the vehicle. The invention includes a toe board extending in a widthwise direction of the vehicle, the toe board being provided in a front part of the vehicle for partitioning an engine compartment containing a power unit therein and a passenger compartment, a pair of front side frames provided by being spaced apart from each other in a widthwise direction of the vehicle, the front side frames extending in a lengthwise direction from a front part of the vehicle to a lower surface of a floor of the passenger compartment, the front side frames being downwardly bent when contacting the toe board, a toe board cross member extending in a widthwise direction of the vehicle between the front side frames so as to connect the front side frames with each other, the toe board cross member and the toe board defining a structure having a closed cross section; and front suspension member supports provided on the front side frames, the toe board cross member connecting the front suspension member supports to each other.
A further object of the present invention is to provide a front structure of a vehicle which prevents the toe board from directly receiving an impact load when the impact load is applied to the vehicle, and minimizes deformation of the front suspension members in a widthwise direction of the vehicle when a force is applied in a widthwise direction, and hence prevents the front suspension members from geometry change and increases driving stability of the vehicle. The invention includes an upper member forming a closed cross section extending in a widthwise direction of the vehicle, the upper member being interposed between the toe board and each of the front side frames at positions where the front side frames are brought into contact with the toe board, and a lower member forming a closed cross section extending in a widthwise direction of the vehicle at a position lower than the upper member, the lower member connecting the positions in the vicinity of the front suspension member supports to each other, or the lower member connecting the front suspension member supports to each other.
Still another object of the present invention is to provide a front structure of a vehicle which absorbs vibration transmitted from the power unit, disperses the vibration, and controls noise generation caused by the vibration wherein the toe board cross member supports a rear part of the power unit provided in the engine compartment. The rigid structure with the closed cross section supports the power unit.